I'm not sure, but the server people have checked everything,

It's been fine. but today I'm getting this...
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Internal Server Error
The server encountered an internal error or misconfiguration and was unable to complete your request.

Please contact the server administrator at webmaster@flexenergyserver.co.uk to inform them of the time this error occurred, and the actions you performed just before this error.

More information about this error may be available in the server error log.

Additionally, a 500 Internal Server Error error was encountered while trying to use an ErrorDocument to handle the request.

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Any help would be appreciated:)